1. Field of the Disclosure
The disclosure relates generally to semiconductor testing, and in particular to electromigration length effect testing.
2. The Prior Art
Dramatic shrinkage in device feature sizes has driven ultra large scale integration (ULSI) into the deep xc2xcxcexc regime. However, electromigration (EM)-induced interconnect failures have continued to be one important factor in long-term device reliability.
Electromigration is caused by the momentum exchange between metal ions and accelerated electrons, and can result in the displacement of the metallic ions comp rising an interconnect. EM may be especially prominent at higher temperatures and current densities, and can contribute to failures such as open circuits, particularly when coupled with tensile stress; or short circuits, when associated with compressive stress.
Apparatus and methods are disclosed for determining the critical length of a conductor. In one aspect, a system may include at least one device under test (DUT) including at least one test strip of a metal under test. The test strip may be formed from a series of segments of the metal under test.
The system may include a plurality of DUTs, and the segments of each of the DUTs may have a unique length. A DUT according to this disclosure may include decoder and selection circuitry and may be embodied within an integrated circuit. The integrated circuit containing said DUT may be mounted on a hot chuck.
The system may be configured to detect electromigration in the DUT using Blech""s law. The system may be further configured to detect a rising voltage drop across the metal strips under test.